Use P4Merge as the Merge Tool for Mercurial Windows

Whenever I do a Mercurial merge on Windows I get a little Visual Studio Dialog popup saying File -nosplash not found. Which is annoying. Especially as I have Perforce's excellent p4merge installed.

You can set the merge tool used by Mercurial like so:

Edit %userprofile%\Mercurial.ini

where Edit is your favourite text editor, and %userprofile% is usually C:\Users\username\.
Then add this section to your Mercurial.ini file:

[merge-tools] 
p4.priority = 100 
p4.premerge = True
p4.executable = C:\Program Files\Perforce\p4merge.exe
p4.gui = True 
p4.args = $base $local $other $output

You can change "p4" to anything, so long as you change all occurrences of p4 left of the = signs.
If p4merge.exe is in your path and if you use p4merge as your identifier, then you don't need the executable line:

[merge-tools] 
p4merge.priority = 100 
p4merge.premerge = True
p4merge.gui = True 
p4merge.args = $base $local $other $output